<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <script>

        //concat() 连接两个或多个字符串，并返回连接后的字符串，不改变原字符串

        var str1 = 'hello';
        var str2 = 'world';

        console.log(str1.concat(str2))



    </script>

</body>
</html>